Using watermarking technology, it is possible to insert watermark data or watermarking textures on an original image that are not visible on the original but are revealed in unauthorized reproduction. Such watermarking technology is widely used for article or copy authentication. However, while it is possible to extract the watermark data by image processing through a computing device without being seen by humans, it is not possible to provide a watermarking technique that cannot be extracted in the case of unauthorized copying.
The technical problem to be solved by the present invention is to provide methods of embedding and extracting watermark data that are robust against geometric distortion and low-quality photographing and for which the probability of successfully extracting watermark data for an original image is high, while the probability of successfully extracting the watermark data in the case of unauthorized copying is seriously impaired.
Another technical problem to be solved by the present invention is to provide methods of embedding and extracting watermark data wherein the quality of the original image is not impaired due to the embedding of the watermark data, and it is not revealed whether or not watermark data is embedded.
Yet another technical problem to be solved by the present invention is to provide methods of embedding and extracting watermark data wherein as the size of the original image increases, the size of embeddable watermark data also increases.
Yet another technical problem to be solved by the present invention is to provide methods of embedding and extracting watermark data that minimizes the likelihood that the clues associated with the embedding and extraction methods will be discovered.
Yet another technical problem to be solved by the present invention is to provide methods of embedding and extracting watermark data wherein even if the material on which the image is printed is changed, there is no problem in extracting the watermark data.
Yet another technical problem to be solved by the present invention is to provide embedding and extraction methods that can be applied regardless of the size of the image.
The technical problems of the present invention are not limited to the above-mentioned technical problems; other technical subjects not mentioned may be clearly understood by those skilled in the art from the following description.